Effect of chitosan‐based melatonin composite coating on the quality of minimally processed pomegranate aril‐sacs during cold storage

Abstract

The current study evaluated the potential of chitosan-based melatonin (CH-MT) composite coating to maintain quality and delay senescence of minimally processed pomegranate aril-sacs during refrigerated storage. Mature pomegranate fruit (cv.Wonderful) without physical defects were processed into aril-sacs. Subsequently, the following treatments were applied; distilled water (control), CH 0.5% (w/v), CH+0.1 mM MT, CH+0.4 mM MT, CH+0.8 mM MT, and CH+1 mM MT. Each treatment was applied by immersing the aril-sacs in the coating solution for 3 min and allowed to dry at room temperature. Aril-sacs were then packed in polyethene terephthalate punnets (three to four aril-sacs/punnet) and stored at 5°C and 85% RH for 21 days. Aril color, weight loss, respiration rate, ascorbic acid content, total anthocyanins, browning index, and antioxidant capacity were monitored during storage at 3 days intervals. The study results showed that the CH-MT coating treatments significantly (p < 0.05) delayed the increase in aril-sacs weight loss and respiration rate. These treatments also retained higher aril chroma, ascorbic acid, anthocyanin content, DPPH-radical scavenging activity, and aril-sacs antioxidant power (FRAP). In addition, surface browning development was significantly suppressed in the coated aril-sacs compared with control sacs.However, the effectiveness of CH-MT treatments in maintaining the quality of arilsacs was concentration-dependent, with CH+0.8-1 mM MT treatments showing the best results. Therefore, CH+0.8-1 mM MT treatments are recommended to suppress the development of physiological disorders and maintain the quality of minimally processed pomegranate aril-sacs. Novelty Impact Statement:This study focuses on the development and application of chitosan-melatonin composite coating (CH-MT) as an active and functional formulation to maintain quality and extend the storage life of minimally processed pomegranate aril-sacs. The results showed that incorporating melatonin with chitosan improved the effectiveness of chitosan base coating. This was demonstrated by the CH-MT coating's enhanced retention of ascorbic acid, anthocyanins, radical scavenging activity, and antioxidant power. Further, delaying the increase in aril-sacs surface